I don't think there is a universally agreed upon, published set of rules governing THCD because. Someone please correct me if I'm wrong?

That being said, tradition often carries the weight of rules. It's a sort ontological imperative: "that's how it is."

This is the work of time and culture producing a set of mores that function to create a sense of identity. Insiders dress and act one way, while outsiders dress and act another.

The result is that people who are acculturated or enculturated into the tradition come to view these markers as being correct and normal. Transgression against the norms therefor has the effect of breaking a rule.

Please pardon the academic language!